Structures of the Class 2 Homology Region C2HR

The structures of three cytokine receptor C2HRs and tissue factor (TF) have been determined (see Table I and Chill et al., 2003 Harlos et at, 1994 Josephson et al, 2001 Randal and Kossiakoff, 2001 Thiel et al., 2000 Walter et al, 1995). The general features of the C2HR are shown in Fig. 8. It consists of two /3-sandwich domains, D1 and D2, connected by a short linker containing 1 turn of a- or 3io helix. The cytokine binding site is comprised predominantly of the loops located at the D1 and D2 interface. The N-terminal D1 domain is most distal from the cell membrane, while the G-terminal D2 domain is followed by a short tether of 5-12 amino acids in length before the beginning of the transmembrane helix. 

Sequence comparisons have identified 15 residues that are highly conserved in the domains of the G2HRs. A subset of these residues were used originally to define the HGRII family (Bazan, 1990b). The location of the 

The D1 and D2 domains consist of approximately 100 residues each. Dl/ D1 and D2/D2 comparisons reveal 70 Ca atom pairs maybe superimposed 

Another surprise from the domain comparisons first noted by Walter et al. was the high degree of structural similarity between D2 of the growth 

Entries correspond to r.m.s. deviation in A followed by the number of Ca atom pairs. The percent sequence identity of residues compared is also listed. 

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